Multi-plate heat exchanger with flow rings

ABSTRACT

A compact, low-cost and thermally efficient multi-plate heat exchanger includes a plurality of stamped plates that are stacked adjacent one another in a compact configuration. The plates each have a thin, flat body portion and a sidewall. Inlet and outlet passages are provided in the plates to direct first and second fluids through the stack. The plates are mechanically formed to emboss the plates around the passages. The respective passages for the first fluid are embossed on one direction, while the respective passages for the second fluid are embossed in another direction. The embossing alternates between plates, such that ring grooves are formed between the plates where it is desired to fluidly communicate with a respective passage. A high efficiency, extended surface fin structure and a pair of flow rings are located on each plate. The flow rings are located in the ring grooves for directing fluid between the respective plates. Each of the flow rings includes radial flow openings for evenly distributing the fluid between the plates. The plates are stacked with additional fin structure and ring pairs between each pair of plates, to achieve the thermal requirements of the particular application. The plates are then permanently secured together into a integral structure, such as by brazing.

CROSS-REFERENCE TO RELATED CASES

[0001] The present application claims the benefit of the filing date ofU.S. Provisional Application Ser. No. 60/243,921; filed Oct. 27, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates generally to multi-plate heatexchangers.

BACKGROUND OF THE INVENTION

[0003] Multi-plate heat exchangers are known which allow heat transferbetween two or more fluids. The heat exchangers can be used to heat orcool a primary fluid, using for example, air, water or oil as a secondfluid. Multiple plates are held together and have flow passages for thefluids, which are directed into a fin or corrugated structure betweenthe plates. The fin/corrugated structure increases the surface areabetween the plates to improve the thermal efficiency of the exchanger.

[0004] The flow of one (for example, the primary) fluid is directedthrough a first inlet passage, through the fin structure between twoplates, to a first outlet passage; while the flow of the second fluid isdirected through a second inlet passage, through a separate finstructure between other plates, to a second outlet passage. The platesare stacked adjacent one another in alternating relation such that heattransfer (via convection and conduction) occurs between the fluids andthe plates. The plates are sealed around their periphery and around thepassages to provide a flow path and to separate the fluids. More thantwo fluids can be incorporated by appropriately scaling the number ofplates and adding appropriate inlet and outlet passages. The plates areheld together such as through brazing, soldering or welding or by endplates which squeeze the plates together.

[0005] Multi-plate heat exchangers of this type are appropriate for manyapplications, and can be more thermally efficient as compared tocompeting technologies such as shell-and-tube heat exchangers.

[0006] Various configurations of multi-plate heat exchangers are known,but it is believed many suffer drawback such as a large size,complicated manufacture of the plates and difficult and time-consumingassembly. Many of the plates are mechanically formed so as to include aunitary fin structure. This generally requires complicated,time-consuming and expensive forming operations. The apparatus forpressing the plates together also adds bulk and cost to the exchanger.As such, it is believed there is a demand for a compact, low-cost,thermally-efficient, multi-plate heat exchanger which is appropriate formany applications, and which is simple to manufacture and assemble.

SUMMARY OF THE PRESENT INVENTION

[0007] The present invention provides a compact, low-cost and thermallyefficient multi-plate heat exchanger which is appropriate for manyapplications, and which is simple to manufacture and assemble.

[0008] According to the present invention, the heat exchanger includes aplurality of stamped plates that are stacked adjacent one another in acompact configuration. The plates each have a thin, flat body portionand a sidewall extending around the periphery of the body portion. Inletand outlet passages are provided in the plates to direct first andsecond fluids through the plate stack. The plates are mechanicallyformed to emboss the plates around the passages. The respective passagesfor the first fluid are embossed in one direction, while the respectivepassages for the second fluid are embossed in another (opposite)direction. The embossing alternates between plates, such that ringgrooves are formed between the plates where it is desired to fluidlycommunicate with a respective passage.

[0009] A high efficiency, extended-surface fin structure, and a pair offlow rings are located on each plate. The fin structure is preferably aseparate component from the plates and can have any type of convolutedgeometry appropriate for the particular application. The fins are formedwith an appropriate height, and from an appropriate material. The flowrings are located in the ring grooves for directing fluid through thefin structure between the respective plates. Each of the flow ringsincludes a pair of annular body portions separated by a series ofsupport members. The flow rings are sized to bound the flow passage, andeach includes radial flow openings between the support members forevenly distributing the fluid through the fin structure. The thicknessand configuration of the flow rings can be varied so as to easilycustomize the flow for a particular application. The plates are stackedwith additional fin structure and ring pairs between each pair ofplates, to achieve the thermal requirements of the particularapplication.

[0010] The plates are permanently secured together into an integralstructure, preferably by cladding or spraying the plates with a brazematerial, and then heating the plates in a furnace.

[0011] The flow rings provide a flow of one fluid between a specific setof plates—without allowing leakage to the fluid flow through an adjacentplate set. The plates and flow rings distribute fluid evenly across theentire plate structure and utilize the entire fin structure. The ringscan also be easily configured to customize the flow between any of theplates. The separate fin structure and flow rings are easy tomanufacture and assemble with the plates. The separate fin structurealso allows the plates to be more compact—as compared to forming theplates with a unitary fin structure. The separate fin structure alsoallows fin structure of different material to be used, to furthercustomize the heat exchanger for a particular application. In all, athermally efficient exchanger is provided that has a low cost, a compactsize, and which is easy to manufacture and assemble.

[0012] Further features of the present invention will become apparent tothose skilled in the art upon reviewing the following specification andattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a top plan view of a heat exchanger constructedaccording to the principles of the present invention;

[0014]FIG. 2 is a side view of the heat exchanger of FIG. 1;

[0015]FIG. 3 is a cross-sectional side view of the heat exchanger takensubstantially along the plane described by the lines 3-3 of FIG. 1;

[0016]FIG. 4 is a cross-sectional end view of the heat exchanger takensubstantially along the plane described by the lines 4-4 of FIG. 2;

[0017]FIG. 5 is an elevated perspective view of one of the plates of theheat exchanger of FIG. 1 shown with the fin structure and flow rings;

[0018]FIG. 6 is a side view of one of the plates of the heat exchangerof FIG. 1;

[0019]FIG. 7 is a cross-sectional end view of the plate takensubstantially along the plane described by the lines 7-7 of FIG. 6;

[0020]FIG. 8 is a cross-sectional end view of the plate takensubstantially along the plane described by the lines 8-8 of FIG. 6;

[0021]FIG. 9 is an enlarged view of a portion of the plate shown in FIG.8;

[0022]FIG. 10 is a top plan view of a flow ring for the heat exchangerof FIG. 1;

[0023]FIG. 11 is a cross-sectional side view of the flow ring takensubstantially along the plane described by the lines 11-11 of FIG. 10;and

[0024]FIG. 12 is a schematic illustration of the flow path through theheat exchanger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] Referring to the drawings, and initially to FIGS. 1-5, a heatexchanger constructed according to the principles of the presentinvention is indicated generally at 15. The heat exchanger 15 includes aseries of stacked plates as at 17, a fin structure as at 19, and flowrings as at 20. The stacked plates are all thin, flat plates formed ofan appropriate material, preferably a corrosion-resistant sheet metal(such as type 304 Stainless). The plates are shown having a rectangularconfiguration, but the dimension and configuration of the plates canvary depending upon the particular application, i.e., the heat transferrequirement. In one embodiment, it was found that plates having athickness of 0.015 in. was appropriate, but again, this can varydepending upon the particular application. In addition, the number ofplates, and consequently the number of fin structures and flow ring setscan vary depending upon the particular application. In the illustratedembodiment (see FIG. 4), nine plates 17A-17I, eight flow rings 20A-20Hand eight fin structures 19A-19H are shown, however, again, this canvary depending upon the particular application.

[0026] The plates each include an inlet opening 21 and an outlet opening22 for a first fluid; and an inlet opening 23 and an outlet opening 24for a second fluid. The inlet and outlet openings for each fluid arepreferably at opposite ends of the plate and are catty-corner(diagonally-opposite) from each other. The inlet openings and outletopenings can of course be reversed, depending on the connection withinthe fluid system. Appropriate fittings or nipples 25 (see FIG. 12) aresealingly attached to each opening in the uppermost plate 17A tofacilitate the connection within the fluid system. The lowermost plate17I preferably is continuous, that is, it does not include openings21-24, although all other aspects of this plate are the same as theothers.

[0027] Preferably each plate is cladded or sprayed on both sides with anappropriate braze material to facilitate securing the plates together,as will be described herein in more detail.

[0028] Referring to FIGS. 6-9, the plates are each stamped or otherwisemechanically formed to create embossments (i.e., a raised or indentedportion) around the openings. Two sets of plates are provided, with adifferent embossment configuration provided for each set. In one set(plates 17A, 17C, 17E, 17G, 17I), each plate end includes a firstembossment 28 bounding outlet opening 24 projecting outwardly (upwardly)away from the upper surface 29 of the plate, and a second embossment 31bounding outlet opening 22 projecting outwardly (downwardly) away fromthe lower surface 32 of the plate. The opposite end of each plateincludes a similar structure, however, preferably the embossments arereversed, that is, a third embossment 34 bounds inlet opening 21 andprojects outwardly (downwardly) away from the lower surface 32 of theplate; while a fourth embossment 36 bounds outlet opening 23 andprojects outwardly (upwardly) away from the upper surface 29. Theembossments 28 and 36 are preferably co-planar with one another; whilethe embossments 31 and 34 are preferably co-planar with one another. Theterms “upper” and “lower” are used herein only for ease of describingthe relative position of the various components, and it is noted thatthe heat exchanger may be oriented in any direction appropriate for theparticular application.

[0029] The other set of plates (plates 17B, 17D, 17F, 17H) also haveembossments, however the embossments are reversed, with the embossmentbounding outlet opening 24 projecting outwardly (downwardly) away fromthe lower surface of the plate, and the second embossment boundingoutlet opening 22 projecting outwardly (upwardly) away from the uppersurface of the plate. Similarly, the opposite end of each plate in thisset includes a third embossment 34 bounding inlet opening 21 andprojecting outwardly (upwardly) away from the upper surface of theplate; and a fourth embossment bounding outlet opening 23 and projectingoutwardly (downwardly) away from the lower surface of the plate. Allother aspects of the plates of this set are the same as in the firstset.

[0030] Each embossment defines an annular ring groove surrounding therespective opening. As shown for example in FIG. 9, embossment 34defines an annular, flat ring groove 40 which completely surroundsopening 21 and opens outwardly from the lower surface 32. Likewise, anannular, flat ring groove is provided by embossment 31 surroundingopening 22 opening outwardly (downwardly) from lower surface 32; whileannular, flat ring grooves are provided by embossments 28 and 36surrounding openings 24 and 23, respectively, but opening outwardly(upwardly) from upper surface 29.

[0031] Each plate also includes a short lip or sidewall as at 46bounding the periphery of the plate and extending outwardly (downwardly)from the lower surface 32. The sidewall 46 allows the plates to bestacked one on top the other in adjacent, surface-to-surface relation,with the sidewall providing a peripheral seal with an adjacentunderlying plate, as will be described herein in more detail. Thesidewall projects away from the plate considerably further than theembossments. In one embodiment, the embossments projected outwardly fromthe surface of the plate about 0.081 in., while the sidewall projectedoutwardly from the plate about 0.375 inches. But again, this can varydepending upon the particular application.

[0032] In any case, the fin structure 19 is disposed across the majorityof the plate. The fin structure 19 comprises any type of convolutedgeometry appropriate for the particular application, such as lancedoffset, wavy, plain or any other surface configuration, and the fins canbe formed with an appropriate height, and of an appropriate density andmaterial. Preferably the fin structure is formed from a light weight,thermally efficient material (e.g., type 304 Stainless), and isrelatively thin (less than the height of the sidewall 46), so that theheat exchanger assembly is relatively compact and yet has a considerablesurface area. The fin structure preferably extends essentially fromside-to-side of the plates, and has a geometry to direct fluid from oneend of the plates directly to the other. The fin structure is preferablyformed of a single piece, although it could also be formed from multiplepieces laid end-to-end. The fin structure is preferably a separate piecefrom the plates, and then located in the area of the plates betweenopenings 21, 23 and 22, 24.

[0033] The flow rings 20 are illustrated in FIGS. 10 and 11. Each flowring has an upper annular body portion 50 and a lower annular bodyportion 52, separated by a series of axial support members as at 54. Theupper and lower annular body portions are preferably thin and flat andare supported parallel (co-planar) to one another. The annular bodyportions 50, 52 have essentially the same geometry as the ring grooves40, such that the flow rings fit easily within each groove. The supportmembers define radial flow passages around the circumference of the flowring to facilitate the even distribution of fluid. The number andgeometry of the support members can vary, depending upon the particularapplication. In one embodiment, twelve evenly-spaced support memberswere provided, which comprised approximately 30% of the totalcircumferential area of the flow ring. The support members in theillustrated embodiment extend between the inner diameters of the upperand lower annular body portions, and projected radially inward a shortamount, however the geometry of the support members can vary dependingupon the particular application, with the number and circumferentiallength of the support members influencing the flow through the ring.

[0034] The annular body portions 50, 52 and support members 54 of theflow rings are preferably formed unitarily (in one piece) for ease ofmanufacture, although they could also be formed in multiple pieces andsecured (e.g., brazed, welded, etc.) together. The flow rings can alsohave different configurations (arrangement of support members, length ofsupport members, etc.) to vary the fluid flow through the respectiveopening, as will be described herein in more detail.

[0035] The heat exchanger is assembled by locating a pair of flow ringsand the fin structure between a pair of plates, one plate being fromeach set. The plates are arranged such that a pair of embossments of oneinlet and one outlet opening are spaced somewhat apart from one another,while a pair of embossments from the other inlet and other outletopening are in adjacent, surface-to-surface relation to each other. Theflow rings are positioned in the ring grooves between the spaced-apartembossments, and fit essentially flush between the opposing ringgrooves. The flow rings and contacting embossments space the platesapart sufficiently such that the fin structure can be locatedtherebetween. In this way, a flow path is provided through the one inletopening, axially into and radially outward through one flow ring,through the fin structure, and radially into and axially out of theother flow ring. The pair of plates therefore direct one fluid acrossthe plate structure, and allow convection and conduction to occurbetween the fluid and the fin structure.

[0036] Similarly, another plate, fin structure and pair of flow ringsare located on one of the first two plates, the additional plate being aplate from the other set, such that the embossments for the other inletand outlet openings are spaced apart from one another, while theembossments for the first inlet and outlet openings are in adjacent,surface-to-surface relation. The flow rings are then located between theembossments which are spaced-apart from each other, and another finstructure is located between the plates. In this way, a second flow pathis provided for a second fluid through the other inlet opening, acrossthe other fin structure, to the other outlet opening. Conduction occursacross the adjoining plate such that thermal transfer occurs between thefluids.

[0037] To prevent leakage between the plates, the plates are sealedtogether, such as by brazing, into an integral structure. The plates canbe heated such that the cladding brazes the plates together, such as atthe tips of the fin structure contacting the plates, and along thecontacting flat surfaces of the flow rings. The flat, surface-to-surfacecontact between the contacting embossments facilitates a leak-free sealbetween the plates, while the inner plate surfaces and the surfaces ofthe annular body portions of the flow rings facilitates securing theflow rings to the plates. The sidewall along the periphery of the platesis also brazed to the sidewall of an adjacent plate. As such, the flowpaths of the two fluids are completely fluidly separated between theplates. Other means such as welding, soldering or presses, can beprovided to secure the plates to one another, and although lesspreferred, may be appropriate in certain applications.

[0038] The number of plates, fin structures and flow rings can be scaledup or down depending upon the particular application. The flow rings arelocated between the spaced apart embossments, and therefore alternatelocations across the width of the plate stack. More than two inletopenings and outlet openings can also be provided, to introduce three ormore fluids between the plates. In this case, further embossments wouldbe created and additional flow rings would be used. This is easilyaccomplished.

[0039] As should be appreciated, the flow rings can be sized so as tospace the plates varying distances apart from one another to increase ordecrease the flow between the plates. As illustrated in FIG. 12, flowrings 20B and 20D have a longer axial length than flow rings 20F. Thus,a greater flow will occur between plates 17B and 17C, and 17D and 17E,than between plates 17F and 17G (only seven plates 17A-17G are shown inFIG. 12). The flow ring pairs can also have different configurations(such as by varying the width and/or number of support members), if itdesirable to have a greater or lesser flow of one fluid as compared tothe other. The use of flow rings therefore easily customizes the fluidflow for the particular application.

[0040] The flow rings thereby provide a flow of one fluid between aspecific set of plates—without allowing leakage to the fluid flowthrough an adjacent plate set. The plates and flow rings distributefluid evenly across the entire plate structure and entirely utilize thefin structure. The rings can also be easily configured to customize theflow between any of the plates. The separate fin structure and flowrings are easy to manufacture and assemble with the plates. The separatefin structure also allows the plates to be more compact—as compared toforming the plates with a unitary fin structure. The separate finstructure also allows fin structure of different material to be used, tofurther customize the heat exchanger for a particular application. Inall, a thermally efficient exchanger is provided that is low in cost,has a compact size, and which is easy to manufacture and assemble.

[0041] The principles, preferred embodiments and modes of operation ofthe present invention have been described in the foregoingspecification. The invention which is intended to be protected hereinshould not, however, be construed as limited to the particular formdescribed as it is to be regarded as illustrative rather thanrestrictive. Variations and changes may be made by those skilled in theart without departing from the scope and spirit of the invention as setforth in the appended claims.

What is claimed is:
 1. A heat exchanger for two fluids, said heatexchanger comprising: a plurality of stamped plates, each of said plateshaving a thin, flat body with opposed surfaces, and a unitary sidewallextending around the periphery of the body and projecting outwardly fromone surface thereof such that said plates can be stacked in adjacentrelation to one another, each plate body having a first inlet and afirst outlet passage for a first of the fluids, and a second inlet and asecond outlet passage for a second of the fluids, the respective inletand outlets passages for the respective fluids being aligned with oneanother, a first set of said plates being identical to one another andbeing embossed around the inlet and outlet passages such that theportion of the plate surrounding the first inlet and first outletpassages projects outwardly from the one surface of the plate and theportion of the plate surrounding the second inlet and second outletpassages projects outwardly from the opposite surface of the plate, asecond set of said plates also being identical to one another and beingembossed around the inlet and outlet passages such that the portion ofthe plate surrounding the first inlet and first outlet passages projectsoutwardly from the opposite surface of the plate and the portion of theplate surrounding the second inlet and second outlet passages projectsoutwardly from the one surface of the plate, said plate sets beingalternated, with the one surface of a plate of said first set locatedadjacent the opposite surface of a plate of said second set, such thatring grooves are defined between the adjacent plates; fin structuredisposed between the adjacent plates forming fluid passages; and aplurality of flow rings as separate components from the plates sized tobound the inlet and outlet passages, said flow rings disposed in thering grooves formed between the adjacent plates, said flow rings havingradial flow openings directing fluid flow between the respectivepassages and the fin structure between the respective plates.
 2. Theheat exchanger as in claim 1, wherein said plates, said fin structureand said flow rings are secured together.
 3. The heat exchanger as inclaim 2, wherein said plates, said fin structure and said flow rings arebrazed together.
 4. The heat exchanger as in claim 1, wherein each ofsaid flow rings includes a pair of annular body portions separated bysupport members, the support members being spaced apart from one anotherto define the radial flow openings in the flow rings.
 5. The heatexchanger as in claim 1, further including inlet and outlet fittings forthe heat exchanger, the inlet and outlet fittings located on one of theplates, such that the fluids are introduced into and received from theplates from one end of the plate stack.
 6. A heat exchanger for twofluids, said heat exchanger comprising: a plurality of plates, each ofsaid plates having a thin, flat body with opposed surfaces, and asidewall extending around the periphery of the body such that saidplates can be stacked in adjacent relation to one another, each platehaving inlet and outlet passages, with the plates being embossed aroundthe inlet and outlet passages such that the portion of the platesurrounding the passages projects outwardly away from a surface of theplate, said plate sets being stacked in adjacent relation with ringgrooves defined between the adjacent plates in surrounding relation toat least some of the passages, fin structure disposed between theadjacent plates forming fluid passages; and a plurality of flow rings asseparate components from the plates, sized to bound the inlet and outletpassages, said flow rings disposed in the ring grooves formed betweenthe adjacent plates, said flow rings having flow openings directingfluid flow between the respective passages and the fin structure betweenthe respective plates.
 7. The heat exchanger as in claim 6, wherein saidplates, said fin structure and said flow rings are secured together. 8.The heat exchanger as in claim 7, wherein said plates, said finstructure and said flow rings are brazed together.
 9. The heat exchangeras in claim 6, wherein each of said flow rings includes a pair ofannular body portions separated by support members, the support membersbeing spaced apart from one another to define the radial flow openingsin the flow rings.
 10. The heat exchanger as in claim 6, furtherincluding inlet and outlet fittings for the heat exchanger, the inletand outlet fittings located on one of the plates, such that the fluidsare introduced into and received from the plates from one end of theplate stack.
 11. A heat exchanger for two fluids, said heat exchangercomprising: a pair of plates, each of said plates having a thin, flatbody with opposed surfaces, and a sidewall extending around theperiphery of the body of one of the plates such that said plates can bestacked in adjacent relation to one another, said one plate having inletand outlet passages, with the plates being embossed in the area aroundthe inlet and outlet passages such ring grooves are defined between theadjacent plates in surrounding relation to at least some of thepassages, fin structure disposed between the adjacent plates formingfluid passages; and a pair of flow rings sized to bound the inlet andoutlet passages, said flow rings disposed in the ring grooves formedbetween the adjacent plates, said flow rings having radial flow openingsdirecting fluid flow between the respective passages and the finstructure between the plates.
 12. The heat exchanger as in claim 11,wherein said plates, said fin structure and said flow rings are securedtogether.
 13. The heat exchanger as in claim 12, wherein said plates,said fin structure and said flow rings are brazed together.
 14. The heatexchanger as in claim 11, wherein each of said flow rings includes apair of annular body portions separated by support members, the supportmembers being spaced apart from one another to define the radial flowopenings in the flow rings.
 15. The heat exchanger as in claim 11,further including inlet and outlet fittings for the heat exchanger, theinlet and outlet fittings located on one of the plates, such that thefluids are introduced into and received from the plates from one end ofthe plate stack.
 16. A method for assembling a multi-plate heatexchanger for two fluids, comprising the steps of: locating a pluralityof thin, flat plates in adjacent, stacked relation to one another, eachof said plates including a first inlet and a first outlet passage for afirst of the fluids, and a second inlet and a second outlet passage fora second of the fluids, the respective inlet and outlets passages forthe respective fluids being aligned with one another when the plates arestacked together, a first set of said plates being identical to oneanother and being embossed around the inlet and outlet passages suchthat the portion of the plate surrounding the first inlet and firstoutlet passages projects outwardly from the one surface of the plate andthe portion of the plate surrounding the second inlet and second outletpassages projects outwardly from the opposite surface of the plate, asecond set of said plates also being identical to one another and beingembossed around the inlet and outlet passages such that the portion ofthe plate surrounding the first inlet and first outlet passages projectsoutwardly from the opposite surface of the plate and the portion of theplate surrounding the second inlet and second outlet passages projectsoutwardly from the one surface of the plate, said plate sets beingalternated, with the one surface of a plate of said first set locatedadjacent the opposite surface of a plate of said second set, such thatring grooves are defined between the adjacent plates locating a flowring in the ring groove between adjacent plates; and permanentlysecuring the plates together.
 17. The method as in claim 16, wherein thestep of permanently securing the plates together comprises brazing theplates together.